Mesenchymal Stem/Stromal Cells in Regenerative Medicine: Past, Present, and Future

Recent progress in mesenchymal stem cell-based therapy for acute lung injury

Acute lung injury (ALI) and acute respiratory distress syndrome (ARDS) are life-threatening diseases in critically ill patients. Although pathophysiology of ALI/ARDS has been investigated in many studies, effective therapeutic strategies are still limited. Mesenchymal stem cell (MSC)-based therapy is emerging as a promising therapeutic intervention for patients with ALI. During the last two decades, researchers have focused on the efficacy and mechanism of MSC application in ALI animal models. MSC derived from variant resources exhibited therapeutic effects in preclinical studies of ALI with different mechanisms. Based on this, clinical studies on MSC treatment in ALI/ARDS has been tried recently, especially in COVID-19 caused lung injury. Emerging clinical trials of MSCs in treating COVID-19-related conditions have been registered in past two years. The advantages and potential of MSCs in the defense against COVID-19-related ALI or ARDS have been confirmed. This review provides a brief overview of recent research progress in MSC-based therapies in preclinical study and clinical trials in ALI treatment, as well as the underlying mechanisms.

Peptoid-Cross-Linked Hydrogel Stiffness Modulates Human Mesenchymal Stromal Cell Immunoregulatory Potential in the Presence of Interferon-Gamma

Human mesenchymal stromal cell (hMSC) manufacturing requires the production of large numbers of therapeutically potent cells. Licensing with soluble cytokines improves hMSC therapeutic potency by enhancing secretion of immunoactive factors but typically decreases proliferative ability. Soft hydrogels, however, have shown promise for boosting immunomodulatory potential, which may compensate for decreased proliferation. Here, hydrogels are cross-linked with peptoids of different secondary structures to generate substrates of various bulk stiffnesses but fixed network connectivity. Secretions of interleukin 6, monocyte chemoattractive protein-1, macrophage colony-stimulating factor, and vascular endothelial growth factor are shown to depend on hydrogel stiffness in the presence of interferon gamma (IFN-γ) supplementation, with soft substrates further improving secretion. The immunological function of these secreted cytokines is then investigated via coculture of hMSCs seeded on hydrogels with primary peripheral blood mononuclear cells (PBMCs) in the presence and absence of IFN-γ. Cocultures with hMSCs seeded on softer hydrogels show decreased PBMC proliferation with IFN-γ. To probe possible signaling pathways, immunofluorescent studies probe the nuclear factor kappa B pathway and demonstrate that IFN-γ supplementation and softer hydrogel mechanics lead to higher activation of this pathway. Overall, these studies may allow for production of more efficacious therapeutic hMSCs in the presence of IFN-γ.

Endometrial mesenchymal stromal/stem cells improve regeneration of injured endometrium in mice

BACKGROUND

The monthly regeneration of human endometrial tissue is maintained by the presence of human endometrial mesenchymal stromal/stem cells (eMSC), a cell population co-expressing the perivascular markers CD140b and CD146. Endometrial regeneration is impaired in the presence of intrauterine adhesions, leading to infertility, recurrent pregnancy loss and placental abnormalities. Several types of somatic stem cells have been used to repair the damaged endometrium in animal models, reporting successful pregnancy. However, the ability of endometrial stem cells to repair the damaged endometrium remains unknown.

METHODS

Electrocoagulation was applied to the left uterine horn of NOD/SCID mice causing endometrial injury. Human eMSC or PBS was then injected into the left injured horn while the right normal horn served as controls. Mice were sacrificed at different timepoints (Day 3, 7 and 14) and the endometrial morphological changes as well as the degree of endometrial injury and repair were observed by histological staining. Gene expression of various inflammatory markers was assessed using qPCR. The functionality of the repaired endometrium was evaluated by fertility test.

RESULTS

Human eMSC successfully incorporated into the injured uterine horn, which displayed significant morphological restoration. Also, endometrium in the eMSC group showed better cell proliferation and glands formation than the PBS group. Although the number of blood vessels were similar between the two groups, gene expression of VEGF-α significantly increased in the eMSC group. Moreover, eMSC had a positive impact on the regeneration of both stromal and epithelial components of the mouse endometrium, indicated by significantly higher vimentin and CK19 protein expression. Reduced endometrial fibrosis and down-regulation of fibrosis markers were also observed in the eMSC group. The eMSC group had a significantly higher gene expression of anti-inflammatory factor Il-10 and lower mRNA level of pro-inflammatory factors Ifng and Il-2, indicating the role of eMSC in regulation of inflammatory reactions. The eMSC group showed higher implantation sites than the PBS group, suggesting better endometrial receptivity with the presence of newly emerged endometrial lining.

CONCLUSIONS

Our findings suggest eMSC improves regeneration of injured endometrium in mice.

Ferroptosis: a promising candidate for exosome-mediated regulation in different diseases

Ferroptosis is a newly discovered form of cell death that is featured in a wide range of diseases. Exosome therapy is a promising therapeutic option that has attracted much attention due to its low immunogenicity, low toxicity, and ability to penetrate biological barriers. In addition, emerging evidence indicates that exosomes possess the ability to modulate the progression of diverse diseases by regulating ferroptosis in damaged cells. Hence, the mechanism by which cell-derived and noncellular-derived exosomes target ferroptosis in different diseases through the system Xc-/GSH/GPX4 axis, NAD(P)H/FSP1/CoQ10 axis, iron metabolism pathway and lipid metabolism pathway associated with ferroptosis, as well as its applications in liver disease, neurological diseases, lung injury, heart injury, cancer and other diseases, are summarized here. Additionally, the role of exosome-regulated ferroptosis as an emerging repair mechanism for damaged tissues and cells is also discussed, and this is expected to be a promising treatment direction for various diseases in the future. Video Abstract.

Mesenchymal stem cell-derived exosomes can alleviate GVHD and preserve the GVL effect in allogeneic stem cell transplantation animal models

Background

Mesenchymal stem cells (MSCs) can alleviate graft-versus-host disease (GVHD) in hematopoietic stem cell transplantation (HSCT). MSCs-derived exosomes (MEXs) can mirror the biological function of their parent cells. Whether MEXs can alleviate GVHD like their parent cells or not is unclear. In this study, we investigate the effects of MEXs on GVHD and graft-versus-leukemia (GVL) effect in vitro and in HSCT animal models.

Method

MSCs were produced using bone marrow mononuclear cells (MNCs), and MEXs were separated from the supernatants of MSCs. Electron microscopy, western blot, and nanoparticle tracking analysis (NTA) were used to determine the characteristics of MEXs. The immunomodulatory function of MEXs and their effects on GVHD and GVL were examined in vitro and in vivo.

Result

Like other cell-type derived exosomes, our data revealed that MEXs were also disc-shaped vesicles with a diameter of 100-200 nm under electron microscopy and were positive for the exosomal hallmark proteins. MEXs can notably inhibit the expression of costimulatory molecules and functional cytokine secretion of dendritic cells (DCs). Meanwhile, MEXs can exert suppressive effects on T lymphocyte proliferation and activation. Moreover, MEXs can also encourage the polarization of macrophages toward the M2 type. In animal HSCT models, MEXs can promote the differentiation of Treg cells in spleens, decrease the GVHD score, increase the survival rate of mice, and preserve the cytotoxic antileukemia effects of CD8+ T lymphocytes from recipient mice.

Conclusion

These findings showed that MEXs exert their effects by inhibiting the immunomodulatory function of DCs, macrophages, and T lymphocytes. In the animal model, MEXs ameliorate the clinical symptoms of GVHD, while maintaining the antitumor effects of CD8+ T lymphocytes. Therefore, it can be inferred that MEXs can separate GVHD from GVL in HSCT. Our study suggests that MEXs have broad clinical application potential in the prevention and treatment of GVHD in HSCT in the near future.

MFGE-8 identified in fetal mesenchymal-stromal-cell-derived exosomes ameliorates acute hepatic failure pathology

Liver transplantation is the gold-standard therapy for acute hepatic failure (AHF) with limitations related to organ shortage and life-long immunosuppressive therapy. Cell therapy emerges as a promising alternative to transplantation. We have previously shown that IL-10 and Annexin-A1 released by amniotic fluid human mesenchymal stromal cells (AF-MSCs) and their hepatocyte progenitor-like (HPL) or hepatocyte-like (HPL) cells induce liver repair and downregulate systemic inflammation in a CCl4-AHF mouse model. Herein, we demonstrate that exosomes (EXO) derived from these cells improve liver phenotype in CCl4-induced mice and promote oval cell proliferation. LC-MS/MS proteomic analysis identified MEFG-8 in EXO cargo that facilitates rescue of AHF by suppressing PI3K signaling. Administration of recombinant MFGE-8 protein also reduced liver damage in CCl4-induced mice. Clinically, MEFG-8 expression was decreased in liver biopsies from AHF patients. Collectively, our study provides proof-of-concept for an innovative, cell-free, less immunogenic, and non-toxic alternative strategy for AHF.

Potential role of mesenchymal stem cells in T cell aging

Immunosenescence occurs with progressive age. T cell aging is manifested by immunodeficiency and inflammation. The main mechanisms are thymic involution, mitochondrial dysfunction, genetic and epigenetic alterations, loss of protein stability, reduction of T cell receptor (TCR) repertoire, naïve-memory T cell ratio imbalance, T cell senescence, and lack of effector plasticity. Mesenchymal stem cells (MSCs) are thought to hold great potential as anti-aging therapy. However, the role of MCSs in T cell aging remains elusive. This review makes a tentative summary of the potential role of MSCs in the protection against T cell aging. It might provide a new idea to intervene in the aging of the immune system.

Human umbilical cord-derived mesenchymal stromal cells alleviate liver cirrhosis through the Hippo/YAP/Id1 pathway and macrophage-dependent mechanism

BACKGROUND

Few effective anti-fibrotic therapies are currently available for liver cirrhosis. Mesenchymal stromal cells (MSCs) ameliorate liver fibrosis and contribute to liver regeneration after cirrhosis, attracting much attention as a potential therapeutic strategy for the disease. However, the underlying molecular mechanism of their therapeutic effect is still unclear. Here, we investigated the effect of human umbilical cord-derived mesenchymal stromal cells (hUC-MSCs) in treating liver cirrhosis and their underlying mechanisms.

METHODS

We used carbon tetrachloride (CCl4)-induced mice as liver cirrhosis models and treated them with hUC-MSCs via tail vein injection. We assessed the changes in liver function, inflammation, and fibrosis by histopathology and serum biochemistry and explored the mechanism of hUC-MSCs by RNA sequencing (RNA-seq) using liver tissues. In addition, we investigated the effects of hUC-MSCs on hepatic stellate cells (HSC) and macrophages by in vitro co-culture experiments.

RESULTS

We found that hUC-MSCs considerably improved liver function and attenuated liver inflammation and fibrosis in CCl4-injured mice. We also showed that these cells exerted therapeutic effects by regulating the Hippo/YAP/Id1 axis in vivo. Our in vitro experiments demonstrated that hUC-MSCs inhibit HSC activation by regulating the Hippo/YAP signaling pathway and targeting Id1. Moreover, hUC-MSCs also alleviated liver inflammation by promoting the transformation of macrophages to an anti-inflammatory phenotype.

CONCLUSIONS

Our study reveals that hUC-MSCs relieve liver cirrhosis in mice through the Hippo/YAP/Id1 pathway and macrophage-dependent mechanisms, providing a theoretical basis for the future use of these cells as a potential therapeutic strategy for patients with liver cirrhosis.

Three-Dimensional Cell Cultures: The Bridge between In Vitro and In Vivo Models

Although historically, the traditional bidimensional in vitro cell system has been widely used in research, providing much fundamental information regarding cellular functions and signaling pathways as well as nuclear activities, the simplicity of this system does not fully reflect the heterogeneity and complexity of the in vivo systems. From this arises the need to use animals for experimental research and in vivo testing. Nevertheless, animal use in experimentation presents various aspects of complexity, such as ethical issues, which led Russell and Burch in 1959 to formulate the 3R (Replacement, Reduction, and Refinement) principle, underlying the urgent need to introduce non-animal-based methods in research. Considering this, three-dimensional (3D) models emerged in the scientific community as a bridge between in vitro and in vivo models, allowing for the achievement of cell differentiation and complexity while avoiding the use of animals in experimental research. The purpose of this review is to provide a general overview of the most common methods to establish 3D cell culture and to discuss their promising applications. Three-dimensional cell cultures have been employed as models to study both organ physiology and diseases; moreover, they represent a valuable tool for studying many aspects of cancer. Finally, the possibility of using 3D models for drug screening and regenerative medicine paves the way for the development of new therapeutic opportunities for many diseases.

Zinc enhances the cell adhesion, migration, and self-renewal potential of human umbilical cord derived mesenchymal stem cells

BACKGROUND

Zinc (Zn) is the second most abundant trace element after Fe, present in the human body. It is frequently reported in association with cell growth and proliferation, and its deficiency is considered to be a major disease contributing factor.

AIM

To determine the effect of Zn on in vitro growth and proliferation of human umbilical cord (hUC)-derived mesenchymal stem cells (MSCs).

METHODS

hUC-MSCs were isolated from human umbilical cord tissue and characterized based on immunocytochemistry, immunophenotyping, and tri-lineage differentiation. The impact of Zn on cytotoxicity and proliferation was determined by MTT and Alamar blue assay. To determine the effect of Zn on population doubling time (PDT), hUC-MSCs were cultured in media with and without Zn for several passages. An in vitro scratch assay was performed to analyze the effect of Zn on the wound healing and migration capability of hUC-MSCs. A cell adhesion assay was used to test the surface adhesiveness of hUC-MSCs. Transcriptional analysis of genes involved in the cell cycle, proliferation, migration, and self-renewal of hUC-MSCs was performed by quantitative real-time polymerase chain reaction. The protein expression of Lin28, a pluripotency marker, was analyzed by immunocytochemistry.

RESULTS

Zn at lower concentrations enhanced the rate of proliferation but at higher concentrations (> 100 µM), showed concentration dependent cytotoxicity in hUC-MSCs. hUC-MSCs treated with Zn exhibited a significantly greater healing and migration rate compared to untreated cells. Zn also increased the cell adhesion rate, and colony forming efficiency (CFE). In addition, Zn upregulated the expression of genes involved in the cell cycle (CDC20, CDK1, CCNA2, CDCA2), proliferation (transforming growth factor β1, GDF5, hypoxia-inducible factor 1α), migration (CXCR4, VCAM1, VEGF-A), and self-renewal (OCT4, SOX2, NANOG) of hUC-MSCs. Expression of Lin28 protein was significantly increased in cells treated with Zn.

CONCLUSION

Our findings suggest that zinc enhances the proliferation rate of hUC-MSCs decreasing the PDT, and maintaining the CFE. Zn also enhances the cell adhesion, migration, and self-renewal of hUC-MSCs. These results highlight the essential role of Zn in cell growth and development.

High-glutathione mesenchymal stem cells isolated using the FreSHtracer probe enhance cartilage regeneration in a rabbit chondral defect model

BACKGROUND

Mesenchymal stem cells (MSCs) are a promising cell source for cartilage regeneration. However, the function of MSC can vary according to cell culture conditions, donor age, and heterogeneity of the MSC population, resulting in unregulated MSC quality control. To overcome these limitations, we previously developed a fluorescent real-time thiol tracer (FreSHtracer) that monitors cellular levels of glutathione (GSH), which are known to be closely associated with stem cell function. In this study, we investigated whether using FreSHtracer could selectively separate high-functioning MSCs based on GSH levels and evaluated the chondrogenic potential of MSCs with high GSH levels to repair cartilage defects in vivo.

METHODS

Flow cytometry was conducted on FreSHtracer-loaded MSCs to select cells according to their GSH levels. To determine the function of FreSHtracer-isolated MSCs, mRNA expression, migration, and CFU assays were conducted. The MSCs underwent chondrogenic differentiation, followed by analysis of chondrogenic-related gene expression. For in vivo assessment, MSCs with different cellular GSH levels or cell culture densities were injected in a rabbit chondral defect model, followed by histological analysis of cartilage-regenerated defect sites.

RESULTS

FreSHtracer successfully isolated MSCs according to GSH levels. MSCs with high cellular GSH levels showed enhanced MSC function, including stem cell marker mRNA expression, migration, CFU, and oxidant resistance. Regardless of the stem cell tissue source, FreSHtracer selectively isolated MSCs with high GSH levels and high functionality. The in vitro chondrogenic potential was the highest in pellets generated by MSCs with high GSH levels, with increased ECM formation and chondrogenic marker expression. Furthermore, the MSCs' function was dependent on cell culture conditions, with relatively higher cell culture densities resulting in higher GSH levels. In vivo, improved cartilage repair was achieved by articular injection of MSCs with high levels of cellular GSH and MSCs cultured under high-density conditions, as confirmed by Collagen type 2 IHC, Safranin-O staining and O'Driscoll scores showing that more hyaline cartilage was formed on the defects.

CONCLUSION

FreSHtracer selectively isolates highly functional MSCs that have enhanced in vitro chondrogenesis and in vivo hyaline cartilage regeneration, which can ultimately overcome the current limitations of MSC therapy.

Alpha terpineol directs bone marrow mesenchymal stem cells toward neuronal lineage through regulation of wnt signaling pathway

Central nervous system anomalies give rise to neuropathological consequences with immense damage to the neuronal tissues. Cell based therapeutics have the potential to manage several neuropathologies whereby the differentiated cells are explored for neuronal regeneration. The current study analyzes the effect of a bioactive compound, alpha terpineol (AT) on the differentiation of rat bone marrow derived mesenchymal stem cells (BM-MSCs) toward neuronal lineage, and explores regulation of differentiation process through the study of Wnt pathway mediators. BM-MSCs were cultured and characterized based on their surface markers and tri-lineage differentiation. Safe dose of AT as optimized by 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium bromide assay, was used for the treatment of MSCs. Treated cells were analyzed for the neuronal, astroglial and germ layer transition markers at the gene and protein levels, by quantitative polymerase chain reaction and immunocytochemistry, respectively. Temporal expression of Wnt pathway genes was assessed during the course of neuronal differentiation. AT treated group showed significant upregulation of neuron specific (NSE, MAP2, Tau, Nestin, and NefL) and astroglial (GFAP) genes with positive expression of late neuronal markers. Germ layer transition analysis showed the overexpression of ectodermal markers (NCAM, Nestin, and Pax6), whereas endodermal (AFP, MixL1, and Sox17), and mesodermal (Mesp1 and T Brachyury) markers were also found to be upregulated. Wnt signaling pathway was activated during the initial phase (30 min) of differentiation, which later was downregulated at 1, 3, and 5 h. AT efficiently induces neuronal differentiation of BM-MSCs by regulating Wnt signaling. Overexpression of both early and late neuronal markers indicate their neuro-progenitor state and thus can be utilized as a promising approach in cellular therapeutics to treat various neurodegenerative ailments. In addition, exploration of the molecular pathways may be helpful to understand the mechanism of cell-based neuronal regeneration.

New Sources, Differentiation, and Therapeutic Uses of Mesenchymal Stem Cells 2.0

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The Use of Mesenchymal Stem Cells in the Complex Treatment of Kidney Tuberculosis (Experimental Study)

In recent years, the application of mesenchymal stem cells (MSCs) has been recognized as a promising method for treatment of different diseases associated with inflammation and sclerosis, which include nephrotuberculosis. The aim of our study is to investigate the effectiveness of MSCs in the complex therapy of experimental rabbit kidney tuberculosis and to evaluate the effect of cell therapy on the reparative processes. Methods: To simulate kidney tuberculosis, a suspension of the standard strain Mycobacterium tuberculosis H37Rv (10⁶ CFU) was used, which was injected into the cortical layer of the lower pole parenchyma of the left kidney under ultrasound control in rabbits. Anti-tuberculosis therapy (aTBT) was started on the 18th day after infection. MSCs (5 × 10⁷ cells) were transplanted intravenously after the start of aTBT. Results: 2.5 months after infection, all animals showed renal failure. Conducted aTBT significantly reduced the level of albumin, ceruloplasmin, elastase and the severity of disorders in the proteinase/inhibitor system and increased the productive nature of inflammation. A month after MSC transplantation, the level of inflammatory reaction activity proteins decreased, the area of specific and destructive inflammation in kidneys decreased and the formation of mature connective tissue was noted, which indicates the reparative reaction activation.

Osteogenic Potential of Sheep Mesenchymal Stem Cells Preconditioned with BMP-2 and FGF-2 and Seeded on an nHAP-Coated PCL/HAP/β-TCP Scaffold

Mesenchymal stem cells (MSCs) attract interest in regenerative medicine for their potential application in bone regeneration. However, direct transplantation of cells into damaged tissue is not efficient enough to regenerate large bone defects. This problem could be solved with a biocompatible scaffold. Consequently, bone tissue engineering constructs based on biomaterial scaffolds, MSCs, and osteogenic cytokines are promising tools for bone regeneration. The aim of this study was to evaluate the effect of FGF-2 and BMP-2 on the osteogenic potential of ovine bone marrow-derived MSCs seeded onto an nHAP-coated PCL/HAP/β-TCP scaffold in vitro and its in vivo biocompatibility in a sheep model. In vitro analysis revealed that cells preconditioned with FGF-2 and BMP-2 showed a better capacity to adhere and proliferate on the scaffold than untreated cells. BM-MSCs cultured in an osteogenic medium supplemented with FGF-2 and BMP-2 had the highest osteogenic differentiation potential, as assessed based on Alizarin Red S staining and ALP activity. qRT-PCR analysis showed increased expression of osteogenic marker genes in FGF-2- and BMP-2-treated BM-MSCs. Our pilot in vivo research showed that the implantation of an nHAP-coated PCL/HAP/β-TCP scaffold with BM-MSCs preconditioned with FGF-2 and BMP-2 did not have an adverse effect in the sheep mandibular region and induced bone regeneration. The biocompatibility of the implanted scaffold-BM-MSC construct with sheep tissues was confirmed by the expression of early (collagen type I) and late (osteocalcin) osteogenic proteins and a lack of an elevated level of proinflammatory cytokines. These findings suggest that FGF-2 and BMP-2 enhance the osteogenic differentiation potential of MSCs grown on a scaffold, and that such a tissue engineering construct may be used to regenerate large bone defects.

Bone regeneration materials and their application over 20 years: A bibliometric study and systematic review

Bone regeneration materials (BRMs) bring us new sights into the clinical management bone defects. With advances in BRMs technologies, new strategies are emerging to promote bone regeneration. The aim of this study was to comprehensively assess the existing research and recent progress on BRMs, thus providing useful insights into contemporary research, as well as to explore potential future directions within the scope of bone regeneration therapy. A comprehensive literature review using formal data mining procedures was performed to explore the global trends of selected areas of research for the past 20 years. The study applied bibliometric methods and knowledge visualization techniques to identify and investigate publications based on the publication year (between 2002 and 2021), document type, language, country, institution, author, journal, keywords, and citation number. The most productive countries were China, United States, and Italy. The most prolific journal in the BRM field was Acta Biomaterialia, closely followed by Biomaterials. Moreover, recent investigations have been focused on extracellular matrices (ECMs) (370 publications), hydrogel materials (286 publications), and drug delivery systems (220 publications). Research hotspots related to BRMs and extracellular matrices from 2002 to 2011 were growth factor, bone morphogenetic protein (BMP)-2, and mesenchymal stem cell (MSC), whereas after 2012 were composite scaffolds. Between 2002 and 2011, studies related to BRMs and hydrogels were focused on BMP-2, in vivo, and in vitro investigations, whereas it turned to the exploration of MSCs, mechanical properties, and osteogenic differentiation after 2012. Research hotspots related to BRM and drug delivery were fibroblast growth factor, mesoporous materials, and controlled release during 2002–2011, and electrospinning, antibacterial activity, and in vitro bioactivity after 2012. Overall, composite scaffolds, 3D printing technology, and antibacterial activity were found to have an important intersection within BRM investigations, representing relevant research fields for the future. Taken together, this extensive analysis highlights the existing literature and findings that advance scientific insights into bone tissue engineering and its subsequent applications.

General consensus on multimodal functions and validation analysis of perinatal derivatives for regenerative medicine applications

Perinatal tissues, such as placenta and umbilical cord contain a variety of somatic stem cell types, spanning from the largely used hematopoietic stem and progenitor cells to the most recently described broadly multipotent epithelial and stromal cells. As perinatal derivatives (PnD), several of these cell types and related products provide an interesting regenerative potential for a variety of diseases. Within COST SPRINT Action, we continue our review series, revising and summarizing the modalities of action and proposed medical approaches using PnD products: cells, secretome, extracellular vesicles, and decellularized tissues. Focusing on the brain, bone, skeletal muscle, heart, intestinal, liver, and lung pathologies, we discuss the importance of potency testing in validating PnD therapeutics, and critically evaluate the concept of PnD application in the field of tissue regeneration. Hereby we aim to shed light on the actual therapeutic properties of PnD, with an open eye for future clinical application. This review is part of a quadrinomial series on functional/potency assays for validation of PnD, spanning biological functions, such as immunomodulation, anti-microbial/anti-cancer, anti-inflammation, wound healing, angiogenesis, and regeneration.

Stem cell-based therapies for temporomandibular joint osteoarthritis and regeneration of cartilage/osteochondral defects: a systematic review of preclinical experiments

OBJECTIVES

The aim of this systematic review was to assess the effects of stem cell-based therapies on the treatment of Temporomandibular Joint Osteoarthritis (TMJ-OA) and the regeneration of cartilage/osteochondral defects.

METHODS

Data on preclinical studies evaluating the effectiveness of stem cell-based therapies for treating Temporomandibular Disorders (TMDs) were extracted from PubMed, Web of Science, and Cochrane Library and the grey literature by three independent reviewers. A manual search was performed in the databases, the reference list of review studies, and relevant journals in the field. Compliance with the ARRIVE guidelines was evaluated for quality assessment. SYRCLE's risk of bias tool for animal experimental studies was assessed to define internal validity.

RESULTS

After applying the inclusion and exclusion criteria, 10 studies were included in the qualitative synthesis. Regardless of cell origin, stem cell-based therapeutic approaches induced protective, anti-inflammatory, and chondroregenerative potential in the treatment of TMJ-OA. Regeneration of the cartilage layer on the surface of the condyle was achieved when stem cells were directly flushed into the defect or when delivered within a carrier.

CONCLUSION

Stem cell-based therapies may be considered a promising approach for the treatment of TMJ-OA and for the regeneration of full-thickness cartilage and osteochondral defects in the TMJ. Human studies shall be performed to validate these results found in animals.

Mesenchymal Stem Cell-Derived Small Extracellular Vesicles: A Novel Approach for Kidney Disease Treatment

Globally, kidney disease has become a serious health challenge, with approximately 10% of adults suffering with the disease, and increasing incidence and mortality rates every year. Small extracellular vesicles (sEVs) are 30 nm-100 nm sized nanovesicles released by cells into the extracellular matrix (ECM), which serve as mediators of intercellular communication. Depending on the cell origin, sEVs have different roles which depend on internal cargoes including, nucleic acids, proteins, and lipids. Mesenchymal stem cell (MSCs) exert anti-inflammatory, anti-aging, and wound healing functions mainly via sEVs in a stable and safe manner. MSC-derived sEVs (MSC-sEVs) exert roles in several kidney diseases by transporting renoprotective cargoes to reduce oxidative stress, inhibit renal cell apoptosis, suppress inflammation, and mediate anti-fibrosis mechanisms. Additionally, because MSC-sEVs efficiently target damaged kidneys, they have the potential to become the next generation cell-free therapies for kidney disease. Herein, we review recent research data on how MSC-sEVs could be used to treat kidney disease.

Application progress of nanotechnology in regenerative medicine of diabetes mellitus

In recent years, the development of diabetic regenerative medicine has led to new developments and progress for the clinical treatment of diabetes mellitus and its various complications. Besides, the emergence of nanotechnology has injected new vitality into diabetic regenerative medicine. Nano-stent provides an appropriate direction for the regeneration of islet β cells, retinal tissue, nerve tissue, and wound tissue cells. Conductive nanomaterials promote various tissues' growth. Many nanoparticles also promote wound healing and present other advantages that have solved many potential problems in the practical application of regenerative medicine. In this review, we will summarize the application of nanotechnology in diabetic regenerative medicine.

Liver Regeneration by Hematopoietic Stem Cells: Have We Reached the End of the Road?

The liver is the organ with the highest regenerative capacity in the human body. However, various insults, including viral infections, alcohol or drug abuse, and metabolic overload, may cause chronic inflammation and fibrosis, leading to irreversible liver dysfunction. Despite advances in surgery and pharmacological treatments, liver diseases remain a leading cause of death worldwide. To address the shortage of donor liver organs for orthotopic liver transplantation, cell therapy in liver disease has emerged as a promising regenerative treatment. Sources include primary hepatocytes or functional hepatocytes generated from the reprogramming of induced pluripotent stem cells (iPSC). Different types of stem cells have also been employed for transplantation to trigger regeneration, including hematopoietic stem cells (HSCs), mesenchymal stromal cells (MSCs), endothelial progenitor cells (EPCs) as well as adult and fetal liver progenitor cells. HSCs, usually defined by the expression of CD34 and CD133, and MSCs, defined by the expression of CD105, CD73, and CD90, are attractive sources due to their autologous nature, ease of isolation and cryopreservation. The present review focuses on the use of bone marrow HSCs for liver regeneration, presenting evidence for an ongoing crosstalk between the hematopoietic and the hepatic system. This relationship commences during embryogenesis when the fetal liver emerges as the crossroads between the two systems converging the presence of different origins of cells (mesoderm and endoderm) in the same organ. Ample evidence indicates that the fetal liver supports the maturation and expansion of HSCs during development but also later on in life. Moreover, the fact that the adult liver remains one of the few sites for extramedullary hematopoiesis—albeit pathological—suggests that this relationship between the two systems is ongoing. Can, however, the hematopoietic system offer similar support to the liver? The majority of clinical studies using hematopoietic cell transplantation in patients with liver disease report favourable observations. The underlying mechanism—whether paracrine, fusion or transdifferentiation or a combination of the three—remains to be confirmed.

Comparison of Biological Features of Wild European Rabbit Mesenchymal Stem Cells Derived from Different Tissues

Although the European rabbit is an "endangered" species and a notorious biological model, the analysis and comparative characterization of new tissue sources of rabbit mesenchymal stem cells (rMSCs) have not been well addressed. Here, we report for the first time the isolation and characterization of rMSCs derived from an animal belonging to a natural rabbit population within the native region of the species. New rMSC lines were isolated from different tissues: oral mucosa (rOM-MSC), dermal skin (rDS-MSC), subcutaneous adipose tissue (rSCA-MSC), ovarian adipose tissue (rOA-MSC), oviduct (rO-MSC), and mammary gland (rMG-MSC). The six rMSC lines showed plastic adhesion with fibroblast-like morphology and were all shown to be positive for CD44 and CD29 expression (characteristic markers of MSCs), and negative for CD34 or CD45 expression. In terms of pluripotency features, all rMSC lines expressed NANOG, OCT4, and SOX2. Furthermore, all rMSC lines cultured under osteogenic, chondrogenic, and adipogenic conditions showed differentiation capacity. In conclusion, this study describes the isolation and characterization of new rabbit cell lines from different tissue origins, with a clear mesenchymal pattern. We show that rMSC do not exhibit differences in terms of morphological features, expression of the cell surface, and intracellular markers of pluripotency and in vitro differentiation capacities, attributable to their tissue of origin.

Mesenchymal Stem Cells in Embryo-Maternal Communication under Healthy Conditions or Viral Infections: Lessons from a Bovine Model

Bovine mesenchymal stem cells are a relevant cell population found in the maternal reproductive tract that exhibits the immunomodulation capacity required to prevent embryo rejection. The phenotypic plasticity showed by both endometrial mesenchymal stem cells (eMSC) and embryonic trophoblast through mesenchymal to epithelial transition and epithelial to mesenchymal transition, respectively, is essential for embryo implantation. Embryonic trophoblast maintains active crosstalk via EVs and soluble proteins with eMSC and peripheral blood MSC (pbMSC) to ensure the retention of eMSC in case of pregnancy and induce the chemotaxis of pbMSC, critical for successful implantation. Early pregnancy-related proteins and angiogenic markers are detected as cargo in EVs and the soluble fraction of the embryonic trophectoderm secretome. The pattern of protein secretion in trophectoderm-EVs changes depending on their epithelial or mesenchymal phenotype and due to the uptake of MSC EVs. However, the changes in this EV-mediated communication between maternal and embryonic MSC populations infected by viruses that cause abortions in cattle are poorly understood. They are critical in the investigation of reproductive viral pathologies.

Therapeutic Effects of Citrus Flavonoids Neohesperidin, Hesperidin and Its Aglycone, Hesperetin, on Bone Health

Flavonoids are natural phytochemicals that have therapeutic effects and act in the prevention of several pathologies. These phytochemicals can be found in seeds, grains, tea, coffee, wine, chocolate, cocoa, vegetables and, mainly, in citrus fruits. Neohesperidin, hesperidin and hesperetin are citrus flavonoids from the flavanones subclass that have anti-inflammatory and antioxidant potential. Neohesperidin, in the form of neohesperidin dihydrochalcone (NHDC), also has dietary properties as a sweetener. In general, these flavanones have been investigated as a strategy to control bone diseases, such as osteoporosis and osteoarthritis. In this literature review, we compiled studies that investigated the effects of neohesperidin, hesperidin and its aglycone, hesperetin, on bone health. In vitro studies showed that these flavanones exerted an antiosteoclastic and anti- inflammatory effects, inhibiting the expression of osteoclastic markers and reducing the levels of reactive oxygen species, proinflammatory cytokines and matrix metalloproteinase levels. Similarly, such studies favored the osteogenic potential of preosteoblastic cells and induced the overexpression of osteogenic markers. In vivo, these flavanones favored the regeneration of bone defects and minimized inflammation in arthritis- and periodontitis-induced models. Additionally, they exerted a significant anticatabolic effect in ovariectomy models, reducing trabecular bone loss and increasing bone mineral density. Although research should advance to the clinical field, these flavanones may have therapeutic potential for controlling the progression of metabolic, autoimmune or inflammatory bone diseases.

A New Human Platelet Lysate for Mesenchymal Stem Cell Production Compliant with Good Manufacturing Practice Conditions

Mesenchymal stem cells (MSCs) are classified as advanced therapy medicinal products, a new category of GMP (good manufacturing practice)-compliant medicines for clinical use. We isolated MSCs from 5 bone marrow (BM) samples using human platelet lysate (HPL) instead of foetal bovine serum (FBS). We used a new method of HPL production consisting of treating platelet (PLTs) pools with Ca-Gluconate to form a gel clot, then mechanically squeezing to release growth factors. We compared the new HPL (HPL-S) with the standard (HPL-E) obtained by freezing/thawing cycles and by adding heparin. HPL-S had not PLTs and fibrinogen but the quantity of proteins and growth factors was comparable to HPL-E. Therefore, HPL-S needed fewer production steps to be in compliance with GMP conditions. The number of colonies forming unit-fibroblasts (CFU-F) and the maintenance of stem markers showed no significant differences between MSCs with HPL-E and HPL-S. The cumulative population doubling was higher in MSCs with HPL-E in the earlier passages, but we observed an inverted trend of cell growth at the fourth passage. Immunophenotypic analysis showed a significant lower expression of HLA-DR in the MSCs with HPL-S (1.30%) than HPL-E (14.10%). In conclusion, we demonstrated that HPL-S is an effective alternative for MSC production under GMP conditions.

Astragalus and human mesenchymal stem cells promote wound healing by mediating immunomodulatory effects through paracrine signaling

Background: Skin regeneration from an injury without a scar is still a challenge. Methods: A murine model of a skin wound was treated with a combination of extract of astragalus and exosomes of mesenchymal stem cells (MSCs). CD11b+ and CD45 macrophages were detected and levels of cytokines were tested. Results: The expression of growth factors VEGF, FGF2 and EGF was elevated after treatment administered to MSCs. The administration of ethanolic extract of astragalus decreased the expression of TNF-α, IL-1β and IL-6 and simultaneously increased the levels of IL-10. The combination sped up the process of wound healing. A sustained-release gel with both ingredients was developed to enhance restoration from granulation. Conclusion: The extract of astragalus promotes the efficacy of MSC-derived exosomes in skin repair.

Efficacy of regenerative medicine for alveolar cleft reconstruction: A systematic review and meta-analysis

Objective:

Objective: To analyze the efficacy and complications of regenerative medicine compared to autogenous bone graft for alveolar cleft reconstruction.

Method:

Method: Electronic search was done in PubMed, Scopus, Embase and Cochrane database for studies published until May 2021. No limitations were considered for the type of the included studies. The risk of bias (ROB) of the studies was assessed using the Cochrane Collaborations and NIH quality assessment tool. Meta-analyses were performed to assess the difference in the amount of bone formation and rate of complications. Grading of Recommendations, Assessment, Development and Evaluation (GRADE) was used for analyzing the level of the evidence.

Results:

Results: Among a total of 42 included studies, 21 studies used growth factors, 16 studies delivered cells, and five studies used biomaterials for bone regeneration of the alveolar cleft. Results showed no significant difference in the amount of bone formation between bone morphogenic protein-2 and iliac graft treated patients after six months (P=0.44) and 12 months (P=0.17) follow-up. Besides, higher swelling (OR=9.46,P<0.01) and less infection (OR=0.19,P=0.01) observed in BMP treated patients. Using stem cells can reduce the post-treatment pain (OR=0.04,P=0.01) but it has no significant impact on other complications (P>0.05). Using tissue engineering methods reduced the operation time (SD=1.06,P<0.01). GRADE assessment showed that results regarding the amount of bone formation volume after six and 12 months have low level of evidence.

Conclusion:

Conclusion: Tissue engineering methods can provide a comparable amount of bone formation as of the autogenous graft and reduce some of the complications, operation time and hospitalization duration.

Extracellular Vesicles Derived from Human Liver Stem Cells Attenuate Chronic Kidney Disease Development in an In Vivo Experimental Model of Renal Ischemia and Reperfusion Injury

The potential therapeutic effect of extracellular vesicles (EVs) that are derived from human liver stem cells (HLSCs) has been tested in an in vivo model of renal ischemia and reperfusion injury (IRI), that induce the development of chronic kidney disease (CKD). EVs were administered intravenously immediately after the IRI and three days later, then their effect was tested at different time points to evaluate how EV-treatment might interfere with fibrosis development. In IRI-mice that were sacrificed two months after the injury, EV- treatment decreased the development of interstitial fibrosis at the histological and molecular levels. Furthermore, the expression levels of pro-inflammatory genes and of epithelial-mesenchymal transition (EMT) genes were significantly reverted by EV-treatment. In IRI-mice that were sacrificed at early time points (two and three days after the injury), functional and histological analyses showed that EV-treatment induced an amelioration of the acute kidney injury (AKI) that was induced by IRI. Interestingly, at the molecular level, a reduction of pro-fibrotic and EMT-genes in sacrificed IRI-mice was observed at days two and three after the injury. These data indicate that in renal IRI, treatment with HLSC-derived EVs improves AKI and interferes with the development of subsequent CKD by modulating the genes that are involved in fibrosis and EMT.

New perspectives in regenerative medicine and surgery: the bioactive composite therapies (BACTs)

Regenerative medicine and surgery is a rapidly expanding branch of translational research in tissue engineering, cellular and molecular biology. To date, the methods to improve cell intake, survival, and isolation need to comply with a complex and still unclear regulatory frame, becoming everyday more restrictive and often limiting the effectiveness and outcome of the therapeutic choices. Thus, the authors developed a novel 360° regenerative strategy based on the synergic action of several new components called the bioactive composite therapies (BACTs) to improve grafted cells intake, and survival in total compliance with the legal and ethical limits of the current regulatory frame. The rationale at the origin of this new technology is based on the evidence that cells need supportive substrate to survive in vitro and this observation, applying the concept of translational medicine, is true also in vivo. Bioactive composite mixtures (BACMs) are tailor-made bioactive mixtures containing several bioactive components that support cells' survival and induce a regenerative response in vivo by stimulating the recipient site to act as an in situ real bioreactor. Many different tissues have been used in the past for the isolation of cells, molecules, and growth factors, but the adipose tissue and its stromal vascular fraction (SVF) remains the most valuable, abundant, safe, and reliable source of regenerative components and particularly of adipose-derived stems cells (ADSCs). The role of plastic surgeons as the historical experts in all the most advanced techniques for harvesting, manipulating, and grafting adipose tissue is fundamental in this constant process of expansion of regenerative procedures. In this article, we analyze the main causes of cell death and the strategies for preventing it, and we present all the technical steps for preparing the main components of BACMs and the different mixing modalities to obtain the most efficient regenerative action on different clinical and pathological conditions. The second section of this work is dedicated to the logical and sequential evolution from simple bioactive composite grafts (BACGs) that distinguished our initial approach to regenerative medicine, to BACTs where many other fundamental technical steps are analyzed and integrated for supporting and enhancing the most efficient regenerative activity. Level of Evidence: Not gradable.

Stem Cell Therapy and Its Significance in HIV Infection

Human immunodeficiency virus (HIV) infection is a major global public health issue. Despite this, the only treatment available in mainstay is antiretroviral therapy. This treatment is not curative, it needs to be used lifelong, and there are many issues with compliance and side effects. In recent years, stem cell therapy has shown promising results in HIV management, and it can have a major impact on the future of HIV treatment and prevention. The idea behind anti-HIV hematopoietic stem/progenitor cell (HSPC)-directed gene therapy is to genetically engineer patient-derived (autologous) HSPC to acquire an inherent resistance to HIV infection. Multiple stem-cell-based gene therapy strategies have been suggested that may infer HIV resistance including anti-HIV gene reagents and gene combinatorial strategies giving rise to anti-HIV gene-modified HSPCs. Such stem cells can hamper HIV progression in the body by interrupting key stages of HIV proliferation: viral entry, viral integration, HIV gene expression, etc.Hematopoietic stem cells (HSCs) may also protect leukocytes from being infected. Additionally, genetically engineered HSCs have the ability to continuously produce protected immune cells by prolonged self-renewal that can attack the HIV virus. Therefore, a successful treatment strategy has the potential to control the infection at a steady state and eradicate HIV from patients. This will allow for a potential future benefit with stem cell therapy in HIV treatment.

Assessment of the structural and functional characteristics of human mesenchymal stem cells associated with a prolonged exposure of morphine

The discovery of the expression of opioid receptors in the skin and their role in orchestrating the process of tissue repair gave rise to questions regarding the potential effects of clinical morphine treatment in wound healing. Although short term treatment was reported to improve tissue regeneration, in vivo chronic administration was associated to an impairment of the physiological healing process and systemic fibrosis. Human mesenchymal stem cells (hMSCs) play a fundamental role in tissue regeneration. In this regard, acute morphine exposition was recently reported to impact negatively on the functional characteristics of hMSCs, but little is currently known about its long-term effects. To determine how a prolonged treatment could impair their functional characteristics, we exposed hMSCs to increasing morphine concentrations respectively for nine and eighteen days, evaluating in particular the fibrogenic potential exerted by the long-term exposition. Our results showed a time dependent cell viability decline, and conditions compatible with a cellular senescent state. Ultrastructural and protein expression analysis were indicative of increased autophagy, suggesting a relation to a detoxification activity. In addition, the enhanced transcription observed for the genes involved in the synthesis and regulation of type I collagen suggested the possibility that a prolonged morphine treatment might exert its fibrotic potential risk, even involving the hMSCs.

Effects of Therapy with Fibrin Glue combined with Mesenchymal Stem Cells (MSCs) on Bone Regeneration: A Systematic Review

Cell therapy strategies using mesenchymal stem cells (MSCs) carried in fibrin glue have shown promising results in regenerative medicine. MSCs are crucial for tissue healing because they have angiogenic, anti-apoptotic and immunomodulatory properties, in addition to the ability to differentiate into several specialized cell lines. Fibrin sealant or fibrin glue is a natural polymer involved in the coagulation process. Fibrin glue provides a temporary structure that favors angiogenesis, extracellular matrix deposition and cell-matrix interactions. Additionally, fibrin glue maintains the local and paracrine functions of MSCs, providing tissue regeneration through less invasive clinical procedures. Thus, the objective of this systematic review was to assess the potential of fibrin glue combined with MSCs in bone or cartilage regeneration. The bibliographic search was performed in the PubMed/MEDLINE, LILACS and Embase databases, using the descriptors (“fibrin sealant” OR “fibrin glue”) AND “stem cells” AND “bone regeneration”, considering articles published until 2021. In this case, 12 preclinical and five clinical studies were selected to compose this review, according to the eligibility criteria. In preclinical studies, fibrin glue loaded with MSCs, alone or associated with bone substitute, significantly favored bone defects regeneration compared to scaffold without cells. Similarly, fibrin glue loaded with MSCs presented considerable potential to regenerate joint cartilage injuries and multiple bone fractures, with significant improvement in clinical parameters and absence of postoperative complications. Therefore, there is clear evidence in the literature that fibrin glue loaded with MSCs, alone or combined with bone substitute, is a promising strategy for treating lesions in bone or cartilaginous tissue.

Deciphering the in vivo Dynamic Proteomics of Mesenchymal Stem Cells in Critical Limb Ischemia

Objective

Regenerative therapy using mesenchymal stem cells (MSC) is a promising therapeutic method for critical limb ischemia (CLI). To understand how the cells are involved in the regenerative process of limb ischemia locally, we proposed a metabolic protein labeling method to label cell proteomes in situ and then decipher the proteome dynamics of MSCs in ischemic hind limb.

Methods and Results

In this study, we overexpressed mutant methionyl-tRNA synthetase (MetRS), which could utilize azidonorleucine (ANL) instead of methionine (Met) during protein synthesis in MSCs. Fluorescent non-canonical amino-acid tagging (FUNCAT) was performed to detect the utilization of ANL in mutant MSCs. Mice with hindlimb ischemia (HLI) or Sham surgery were treated with MetRS^mut MSCs or PBS, followed by i.p. administration of ANL at days 0, 2 6, and 13 after surgery. FUNCAT was also performed in hindlimb tissue sections to demonstrate the incorporation of ANL in transplanted cells in situ. At days 1, 3, 7, and 14 after the surgery, laser doppler imaging were performed to detect the blood reperfusion of ischemic limbs. Ischemic tissues were also collected at these four time points for histological analysis including HE staining and vessel staining, and processed for click reaction based protein enrichment followed by mass spectrometry and bioinformatics analysis. The MetRS^mut MSCs showed strong green signal in cell culture and in HLI muscles as well, indicating efficient incorporation of ANL in nascent protein synthesis. By 14 days post-treatment, MSCs significantly increased blood reperfusion and vessel density, while reducing inflammation in HLI model compared to PBS. Proteins enriched by click reaction were distinctive in the HLI group vs. the Sham group. 34, 31, 49, and 26 proteins were significantly up-regulated whereas 28, 32, 62, and 27 proteins were significantly down-regulated in HLI vs. Sham at days 1, 3, 7, and 14, respectively. The differentially expressed proteins were more pronounced in the pathways of apoptosis and energy metabolism.

Conclusion

In conclusion, mutant MetRS allows efficient and specific identification of dynamic cell proteomics in situ, which reflect the functions and adaptive changes of MSCs that may be leveraged to understand and improve stem cell therapy in critical limb ischemia.

Recent trends in stem cell-based therapies and applications of artificial intelligence in regenerative medicine

Stem cells are undifferentiated cells that can self-renew and differentiate into diverse types of mature and functional cells while maintaining their original identity. This profound potential of stem cells has been thoroughly investigated for its significance in regenerative medicine and has laid the foundation for cell-based therapies. Regenerative medicine is rapidly progressing in healthcare with the prospect of repair and restoration of specific organs or tissue injuries or chronic disease conditions where the body’s regenerative process is not sufficient to heal. In this review, the recent advances in stem cell-based therapies in regenerative medicine are discussed, emphasizing mesenchymal stem cell-based therapies as these cells have been extensively studied for clinical use. Recent applications of artificial intelligence algorithms in stem cell-based therapies, their limitation, and future prospects are highlighted.

Mechanical Sensing Element PDLIM5 Promotes Osteogenesis of Human Fibroblasts by Affecting the Activity of Microfilaments

Human skin fibroblasts (HSFs) approximate the multidirectional differentiation potential of mesenchymal stem cells, so they are often used in differentiation, cell cultures, and injury repair. They are an important seed source in the field of bone tissue engineering. However, there are a few studies describing the mechanism of osteogenic differentiation of HSFs. Here, osteogenic induction medium was used to induce fibroblasts to differentiate into osteoblasts, and the role of the mechanical sensitive element PDLIM5 in microfilament-mediated osteogenic differentiation of human fibroblasts was evaluated. The depolymerization of microfilaments inhibited the expression of osteogenesis-related proteins and alkaline phosphatase activity of HSFs, while the polymerization of microfilaments enhanced the osteogenic differentiation of HSFs. The evaluation of potential protein molecules affecting changes in microfilaments showed that during the osteogenic differentiation of HSFs, the expression of PDLIM5 increased with increasing induction time, and decreased under the state of microfilament depolymerization. Lentivirus-mediated PDLIM5 knockdown by shRNA weakened the osteogenic differentiation ability of HSFs and inhibited the expression and morphological changes of microfilament protein. The inhibitory effect of knocking down PDLIM5 on HSF osteogenic differentiation was reversed by a microfilament stabilizer. Taken together, these data suggest that PDLIM5 can mediate the osteogenic differentiation of fibroblasts by affecting the formation and polymerization of microfilaments.

Zinc Sulfate Stimulates Osteogenic Phenotypes in Periosteum-Derived Cells and Co-Cultures of Periosteum-Derived Cells and THP-1 Cells

Coupling between osteoblast-mediated bone formation and osteoclast-mediated bone resorption maintains both mechanical integrity and mineral homeostasis. Zinc is required for the formation, mineralization, growth, and maintenance of bones. We examined the effects of zinc sulfate on osteoblastic differentiation of human periosteum-derived cells (hPDCs) and osteoclastic differentiation of THP-1 cells. Zinc sulfate enhanced the osteoblastic differentiation of hPDCs; however, it did not affect the osteoclastic differentiation of THP-1 cells. The levels of extracellular signaling-related kinase (ERK) were strongly increased during osteoblastic differentiation in zinc sulfate-treated hPDCs, compared with other mitogen-activated protein kinases (MAPKs). Zinc sulfate also promoted osteogenesis in hPDCs and THP-1 cells co-cultured with the ratio of one osteoclast to one osteoblast, as indicated by alkaline phosphatase levels, mineralization, and cellular calcium contents. In addition, the receptor activator of nuclear factor kappa B ligand (RANKL)/osteoprotegerin (OPG) ratio was decreased in the zinc sulfate-treated co-cultures. Our results suggest that zinc sulfate enhances osteogenesis directly by promoting osteoblastic differentiation and osteogenic activities in osteoblasts and indirectly by inhibiting osteoclastic bone resorption through a reduced RANKL/OPG ratio in co-cultured osteoblasts and osteoclasts.

Calcium channels and their role in regenerative medicine

Stem cells hold indefinite self-renewable capability that can be differentiated into all desired cell types. Based on their plasticity potential, they are divided into totipotent (morula stage cells), pluripotent (embryonic stem cells), multipotent (hematopoietic stem cells, multipotent adult progenitor stem cells, and mesenchymal stem cells [MSCs]), and unipotent (progenitor cells that differentiate into a single lineage) cells. Though bone marrow is the primary source of multipotent stem cells in adults, other tissues such as adipose tissues, placenta, amniotic fluid, umbilical cord blood, periodontal ligament, and dental pulp also harbor stem cells that can be used for regenerative therapy. In addition, induced pluripotent stem cells also exhibit fundamental properties of self-renewal and differentiation into specialized cells, and thus could be another source for regenerative medicine. Several diseases including neurodegenerative diseases, cardiovascular diseases, autoimmune diseases, virus infection (also coronavirus disease 2019) have limited success with conventional medicine, and stem cell transplantation is assumed to be the best therapy to treat these disorders. Importantly, MSCs, are by far the best for regenerative medicine due to their limited immune modulation and adequate tissue repair. Moreover, MSCs have the potential to migrate towards the damaged area, which is regulated by various factors and signaling processes. Recent studies have shown that extracellular calcium (Ca²⁺) promotes the proliferation of MSCs, and thus can assist in transplantation therapy. Ca²⁺ signaling is a highly adaptable intracellular signal that contains several components such as cell-surface receptors, Ca²⁺ channels/pumps/exchangers, Ca²⁺ buffers, and Ca²⁺ sensors, which together are essential for the appropriate functioning of stem cells and thus modulate their proliferative and regenerative capacity, which will be discussed in this review.

VE-cadherin-based matrix promoting the self-reconstruction of pro-vascularization microenvironments and endothelial differentiation of human mesenchymal stem cells

Regulating the secretion and endothelial differentiation of human mesenchymal stem cells (hMSCs) plays an important role in the vascularization in tissue engineering and regenerative medicine. In this study, a recombinant cadherin fusion protein consisting of a human vascular endothelial-cadherin extracellular domain and immunoglobulin IgG Fc region (hVE-cad-Fc) was developed as a bioartificial matrix for modulating hMSCs. The hVE-cad-Fc matrix significantly enhanced the secretion of angiogenic factors, activated the VE-cadherin-VEGFR2/FAK-AKT/PI3K signaling pathway in hMSCs, and promoted the endothelial differentiation of hMSCs even without extra VEGF. Furthermore, the hVE-cad-Fc matrix was applied for the surface modification of a poly (lactic-co-glycolic acid) (PLGA) porous scaffold, which significantly improved the hemocompatibility and vascularization of the PLGA scaffold in vivo. These results revealed that the hVE-cad-Fc matrix should be a superior bioartificial ECM for remodeling the pro-vascularization extracellular microenvironment by regulating the secretion of hMSCs, and showed great potential for the vascularization in tissue engineering.

Combined therapy of mesenchymal stem cells with a GLP-1 receptor agonist, liraglutide, on an inflammatory-mediated diabetic non-human primate model

AIMS

Immunomodulation concurrent with the promotion of β-cell function is a strategy used to develop innovative therapies for type 1 diabetes (T1D). Here, we assessed the therapeutic potential of co-administration of human clonal mesenchymal stem (stromal) cells (hBM-cMSCs) and liraglutide as a glucagon-like peptide-1 agonist in a non-human primate model with streptozotocin (STZ)-induced diabetes.

MAIN METHODS

Diabetes was induced through intravenous (i.v.) multiple low-dose (MLD) infusions of STZ at a dose of 30 mg/kg body weight (b.w.) for five consecutive days, followed by two booster injections of 35 mg/kg on days 12 and 19. After 90 days, the diabetic animals were randomly allocated to two groups: The combination therapy group (n = 4) received injections of 1.5 × 10⁶ hBM-cMSCs/kg b.w. through celiac artery by angiography on days 91 and 105 and daily subcutaneous injections of liraglutide (up to 1.8 mg/day) until day 160 while vehicle group received phosphate-buffered saline. The monkeys were assessed for functional, immunological, and histological analysis.

KEY FINDINGS

The combined treatment group had continued reduction in FBG levels up to day 160, which was accompanied by increased b.w., C-peptide, and β-cell function, and decreased HbA1c and fructosamine levels compared to vehicle group. The combined treatment increased Tregs, IL-4, IL-10, and TGF-β1 and decreased IL-6 and IL-1β. Stereological analysis of the pancreatic tissue exhibited more total volume of insulin-secreting islets in the combined treatment group compared to vehicle group.

SIGNIFICANCE

Our findings demonstrated this combined treatment impaired the clinical symptoms of diabetes in this animal model through immunomodulation and β-cell preservation.

Progress in studies on pathological changes and future treatment strategies of obesity-associated female stress urinary incontinence: a narrative review

With the increasing prevalence of obesity worldwide, obesity-related female stress urinary incontinence (FSUI) has become a key health problem. Recent studies indicated that FSUI is primarily caused by obesity-related pathological changes, such as fat droplet deposition, and results in pelvic floor nerve, vascular, and urethral striated muscle injury. Meanwhile, treatments for obesity-associated FSUI (OA-FSUI) have garnered much attention. Although existing OA-FSUI management strategies, including weight loss, pelvic floor muscle exercise, and urethral sling operation, could play a role in symptomatic relief; they cannot reverse the pathological changes in OA-FSUI. The continued exploration of safe and reliable treatments has led to regenerative therapy becoming a particularly promising area of researches. Specifically, micro-energy, such as low-intensity pulsed ultrasound (LIPUS), low-intensity extracorporeal shock wave therapy (Li-ESWT), and pulsed electromagnetic field (PEMF), have been shown to restore the underlying pathological changes of OA-FSUI, which might be related by regulation endogenous stem cells (ESCs) to restore urine control function ultimately in animal experiments. Therefore, ESCs may be a target for repairing pathological changes of OA-FSUI. The aim of this review was to summarize the OA-FSUI-related pathogenesis, current treatments, and to discuss potential therapeutic options. In particular, this review is focused on the effects and related mechanisms of micro-energy therapy for OA-FSUI to provide a reference for future basically and clinical researches.

Mesenchymal stem cells and acellular products attenuate murine induced colitis

Background

Mesenchymal stem cells (MSCs) are a well-established immunomodulatory agent which can also promote tissue repair and regeneration. Recent studies have demonstrated MSCs as a novel therapeutic for inflammatory bowel disease (IBD), a chronic idiopathic inflammatory disorder of the gastrointestinal tract. However, the precise role of MSCs in regulating immune responses is controversial, and its significance in the pathogenesis remains IBD undefined. In addition, MSCs’ acellular product, extracellular vesicles (EVs), may also play an important role in the armamentarium of therapeutics, but how EVs compare to MSCs remains unknown due to the lack of side-by-side comparative investigation. We herein compared MSCs and MSC-derived EVs for the treatment of IBD using a DSS-induced colitis model.

Methods

A DSS-induced colitis model was used. At day 4, mice received adipose-derived MSCs, MSC-derived EVs, or placebo. Weight loss, stool consistency, and hematochezia was charted. At day 8, murine colons were harvested, histologic analysis performed, and serum/tissue cytokine analysis conducted.

Results

MSCs and EVs demonstrated equivalent immunosuppressive function in DSS-treated mice through decreased colonic lymphocyte infiltration and attenuated disease severity after both MSC and EV treatment. Furthermore, both MSCs and EVs have an equivalent ability to inhibit inflammation in the DSS colitis model by inhibiting JAK, JNK 1/2, and STAT3 signaling.

Conclusions

These results suggest that (i) both MSCs and EVs are effective therapeutic candidates for a DSS-induced mouse colitis model, (ii) MSCs and EVs have similar immunosuppressive and anti-inflammatory functions, and (iii) EVs may present a novel future therapeutic for the treatment of IBD.

Extracellular Vesicles from SOD3-Transduced Stem Cells Exhibit Improved Immunomodulatory Abilities in the Murine Dermatitis Model

The immunoregulatory abilities of mesenchymal stem cells (MSCs) have been investigated in various autoimmune and allergic diseases. However, the therapeutic benefits observed in preclinical settings have not been reproducible in clinical trials. This discrepancy is due to insufficient efficacy of MSCs in harsh microenvironments, as well as batch-dependent variability in potency. Therefore, to achieve more beneficial and uniform outcomes, novel strategies are required to potentiate the therapeutic effect of MSCs. One of simple strategies to augment cellular function is genetic manipulation. Several studies showed that transduction of antioxidant enzyme into cells can increase anti-inflammatory effects. Therefore, we evaluated the immunoregulatory abilities of MSCs introduced with extracellular superoxide dismutase 3 (SOD3) in the present study. SOD3-overexpressed MSCs (SOD3-MSCs) reduced the symptoms of murine model of atopic dermatitis (AD)-like inflammation, as well as the differentiation and activation of various immune cells involved in AD progression. Interestingly, extracellular vesicles (EVs) isolated from SOD3-MSCs delivered SOD3 protein. EVs carrying SOD3 also exerted improved therapeutic efficacy, as observed in their parent cells. These results suggest that MSCs transduced with SOD3, an antioxidant enzyme, as well as EVs isolated from modified cells, might be developed as a promising cell-based therapeutics for inflammatory disorders.

Mesenchymal Stem Cells (MSCs) as a Potential Therapeutic Strategy in COVID-19 Patients: Literature Research

In 2019, an outbreak of an unknown coronavirus – SARS-CoV-2 – responsible for COVID-19 disease, was first reported in China, and evolved into a pandemic of huge dimensions and raised serious concerns for global health. The number of critical cases continues to increase dramatically, while vaccines and specific treatments are not yet available. There are several strategies currently being studied for the treatment of adverse symptoms of COVID-19, that encompass Acute Lung Injury (ALI)/Acute Respiratory Distress Syndrome (ARDS), extensive pulmonary inflammation, cytokine storm, and pulmonary edema, due to virus-induced pneumonia. Mesenchymal stem cells (MSCs) are at the origin of new revolutionary treatments, which may come to be applied in such as Regenerative Medicine, Immunotherapy, Tissue Engineering, and Cell and Molecular Biology due to immunomodulation and anti-inflammatory activity. MSCs have already been studied with positive outcomes for other lung pathologies, thus representing and being identified as an important opportunity for the treatment of COVID-19. It has recently been shown that these cells allow hopeful and effective therapies for serious or critical COVID-19, minimizing its adverse symptoms. In this study we will analyze the MSCs, their origin, differentiation, and therapeutic potential, making a bridge with the COVID-19 disease and its characteristics, as a potential therapeutic strategy but also reporting recent studies where these cell-based therapies were used for the treatment of COVID-19 patients.

Hemovac blood after total knee arthroplasty as a source of stem cells

Background

With increasing life expectancy, stem cell therapy is receiving increasing attention. However, its application is restricted by ethical concerns. Hence a need exists for design of safe procedures for stem cell procurement. Here, we investigated whether hemovac blood (HVB) is an appropriate stem cell source.

Methods

HVB concentrates (HVBCs) from 20 total knee arthroplasty (TKA) patients and bone marrow aspirate (BMA) concentrates (BMACs) from 15 patients who underwent knee cartilage repair were comparatively evaluated. A bone marrow aspiration needle was inserted into the anterior superior iliac spine. Aspiration was performed using a 50-mL syringe, including 4 mL of anticoagulant, followed by centrifugation to obtain BMACs. To obtain HVBCs, blood was aspirated from the hemovac immediately after TKA surgery. Different cell types were enumerated. Isolation of BMA and HVB mononuclear cells was performed using density gradient centrifugation. Non-hematopoietic fibroblast colonies were quantified by colony forming unit-fibroblast assay surface marker analysis of HVB, HVBC, BMA, and BMAC was performed via flow cytometry. Mesenchymal stem cells (MSCs) isolated from HVBCs and BMACs were examined for osteogenic, adipogenic, and chondrogenic differentiation potential. Gene expression analysis was performed by quantitative real-time polymerase chain reaction (qRT-PCR).

Results

The number of cells from HVB and HVBC was significantly lower than from BMA and BMAC; however, the number of colonies in HVBC and BMAC did not differ significantly (P>0.05). Isolated cells from both sources had a fibroblast-like appearance, adhered to culture flasks, and formed colonies. Under different culture conditions, MSC-specific surface markers (CD29, CD44, CD90, CD105), osteogenic markers [RUNX2, osteopontin, osteocalcin, and alkaline phosphatase (ALP)] and adipogenic markers (PPARγ and C/EBPα) were expressed. Moreover, SOX9, type II collagen, and aggrecan were significantly upregulated upon chondrogenic differentiation.

Conclusions

HVB from TKA patients is a useful source of stem cells for research.

Introduction for Stem Cell-Based Therapy for Neurodegenerative Diseases

Neurodegenerative diseases (NDs) are a group of neurological diseases caused by the progressive degeneration of neurons and glial cells in the brain and spinal cords. Usually there is a selective loss of specific neuronal cells in a restricted brain area from any neurodegenerative diseases, such as dopamine (DA) neuron death in Parkinson disease (PD) and motor neuron loss in amyotrophic lateral sclerosis (ALS), or a widespread degeneration affecting many types of neurons in Alzheimer's disease (AD). As there is no effective treatment to stop the progression of these neurodegenerative diseases, stem cell-based therapies have provided great potentials for these disorders. Currently transplantation of different stem cells or their derivatives has improved neural function in animal models of neurodegenerative diseases by replacing the lost neural cells, releasing cytokines, modulation of inflammation, and mediating remyelination. With the advance in somatic cell reprogramming to generate induced pluripotent stem cells (iPS cells) and directly induced neural stem cells or neurons, pluripotent stem cell can be induced to differentiate to any kind of neural cells and overcome the immune rejection of the allogeneic transplantation. Recent studies have proved the effectiveness of transplanted stem cells in animal studies and some clinical trials on patients with NDs. However, some significant hurdles need to be resolved before these preclinical results can be translated to clinic. In particular, we need to better understand the molecular mechanisms of stem cell transplantation and develop new approaches to increase the directed neural differentiation, migration, survival, and functional connections of transplanted stem cells in the pathological environment of the patient's central nerve system.

Stem cell derived extracellular vesicles for vascular elastic matrix regenerative repair

Abdominal aortic aneurysms (AAA) are localized expansions of the abdominal aorta that develop due to chronic proteolytic disruption of the structural extracellular matrix (ECM) components (elastin and collagen) within the aorta wall. Major limitations in arresting or reversing AAAs lie in naturally poor and aberrant regeneration and repair of elastic matrix structures in the aorta wall. Bone marrow derived mesenchymal stem cells (BM-MSCs) have emerged as a promising regenerative tool and their therapeutic effects are also known to be effected through their paracrine secretions. Extracellular vesicles (EVs) present in these secretions have emerged as critical cellular component in facilitating many therapeutic benefits of MSCs. EV treatment is thus potentially appealing as a stem cell-inspired cell-free approach to avoid possible phenotypic plasticity of MSCs in vivo. In this study, we investigated the thus far unknown effects of BM-MSC derived EVs on vascular elastic matrix repair in the context of AAA treatment. EVs isolated from BM-MSC source were characterized and their pro-regenerative and their anti-proteolytic effects were evaluated on our established in vitro experimental conditions derived from AAA rat model. Our studies revealed the efficacy of BM-MSC derived EVs in attenuating the proteolytic activity and also in imparting elastic matrix regenerative benefits under aneurysmal environment. Interestingly, compared to cell culture conditioned media (CCM), EVs demonstrated superior regenerative and anti-proteolytic benefits in a proteolytic injury culture model of AAA. From these studies, it appears that EVs derived from BM-MSCs could be beneficial in undertaking a reparative effort in AAA induced degeneration of vascular tissue. Statement of Significance Abdominal aortic aneurysms (AAAs) are localized, rupture-prone expansions of the aorta which result from loss of wall flexibility due to enzymatic breakdown of elastic fibers. There are no established alternatives to surgery, which possess high risk for the mostly elderly patients. Our previous studies have established the elastic regenerative and reparative effect of cell culture secretions derived from adult stem cell source. In this study, we propose to isolate extracellular vesicles (exosomes) from these secretions and evaluate their regenerative benefits in AAA smooth muscle cell culture model. This simple and innovative treatment approach has the potential to arrest or reverse AAA growth to rupture, not possible so far.

Application of mesenchymal stem cell for tympanic membrane regeneration by tissue engineering approach

Regeneration is a biological process of cell renewal that takes place in damaged tissues or organs. It is naturally stimulated by the release of different growth factors, cytokines, surface molecules, and stem cells at the wounded sites. The tympanic membrane (TM) is an essential component of the hearing process in the auditory system, which can amplify and transmit sound vibrations through a chain of mobile ossicles. Middle ear infection, external sound pressure, insertion of sharp objects into the ear, and severe trauma are the main causes of TM perforations (TMPs), which could result in deficient hearing function. So far, otolaryngologists have employed surgical procedures (myringoplasty or tympanoplasty) to close the perforated eardrum. Because of limitations such as side effects, discomfort, and high cost to patients, there is a need for better alternatives to surgical procedures. Tissue engineering is a promising tool that can overcome the operational risk and restore, maintain, and improve the function of the TM using a range of biocompatible scaffolds, commercially available growth factors, and stem cells. Currently, multipotent mesenchymal stem cells (MSCs) are a good therapeutic option for the treatment of TMPs because of their self-renewing, and autocrine and paracrine activities. As there are fewer risks of isolation in the use of MSCs for the treatment of TMPs, they are more advantageous for tissue regeneration. The delivery of either MSCs alone or a combination of MSCs with biomaterials and growth factors (GFs) at the ruptured TM sites may enhance the activation of epithelial stem cell markers and increase the migration and proliferation of keratinocytes resulting in faster closure of TMPs. This review focuses on the current strategies used to treat TMPs and the importance of MSCs in TM regeneration. Particularly, we have discussed the synergistic effect of MSCs and scaffolds or GFs or scaffolds/GFs in TM regeneration. Finally, with the advancement of tissue engineering technologies such as 3D and 4D bioprinting, MSCs can be used to design patient-specific scaffolds, which may contain physical and chemical guidance cues to improve the extent and rate of targeted tissue regeneration.

Application of Stem Cell-Derived Extracellular Vesicles in Allergic Airway Diseases

Mesenchymal stem cells (MSCs) have been reported to be promising candidates for the treatment of allergic airway diseases. However, MSCs themselves have several problems including immune rejection, risk of aneuploidy, difficulty of handling, and tumorigenicity. An increasing number of studies demonstrated that administration of conditioned media or extracellular vesicles (EVs) released by MSCs is as effective as the MSCs themselves in suppression of allergic airway inflammation. EVs can exert their effects by delivering their contents such as proteins, mRNAs, and microRNAs to recipient cells. Furthermore, the administration of MSCs-derived EVs may reduce potential safety risks associated with stem cell therapy, suggesting that MSCs-derived EVs may be a promising alternative to cell therapy for allergic airway diseases. This review examines the current understanding of the immunomodulatory properties of MSCs-derived EVs and its therapeutic implication for allergic airway diseases.

Sarcopenia: Current treatments and new regenerative therapeutic approaches

Sarcopenia is characterized by loss of muscle and reduction in muscle strength that contributes to higher mortality rate and increased incidence of fall and hospitalization in the elderly. Mitochondria dysfunction and age-associated inflammation in muscle are two of the main attributors to sarcopenia progression. Recent clinical trials on sarcopenia therapies such as physical exercise, nutraceutical, and pharmaceutical interventions have revealed that exercise is the only effective strategy shown to alleviate sarcopenia. Unlike nutraceutical and pharmaceutical interventions that showed controversial results in sarcopenia alleviation, exercise was found to restore mitochondria homeostasis and dampen inflammatory responses via a complex exchange of myokines and osteokines signalling between muscle and bone. However, as exercise have limited benefit to immobile patients, the use of stem cells and their secretome are being suggested to be novel therapeutics that can be catered to a larger patient population owing to their mitochondria restoration effects and immune modulatory abilities. As such, we reviewed the potential pros and cons associated with various stem cell types/secretome in sarcopenia treatment and the regulatory and production barriers that need to be overcome to translate such novel therapeutic agents into bedside application.

Translational potential: This review summarizes the causes underlying sarcopenia from the perspective of mitochondria dysfunction and age-associated inflammation, and the progress of clinical trials for the treatment of sarcopenia. We also propose therapeutic potential of stem cell therapy and bioactive secretome for sarcopenia.

Human umbilical cord derived mesenchymal stem cells in peripheral nerve regeneration

BACKGROUND

Peripheral nerve injury can occur as a result of trauma or disease and carries significant morbidity including sensory and motor loss. The body has limited ability for nerve regeneration and functional recovery. Left untreated, nerve lesions can cause lifelong disability. Traditional treatment options such as neurorrhaphy and neurolysis have high failure rates. Surgical reconstruction with autograft carries donor site morbidity and often provide suboptimal results. Mesenchymal stem cells (MSCs) are known to have promising regenerative potential and have gained attention as a treatment option for nerve lesions. It is however, unclear whether it can be effectively used for nerve regeneration.

AIM

To evaluate the evidence for the use of human umbilical cord derived MSCs (UCMSCs) in peripheral nerve regeneration.

METHODS

We carried out a systematic literature review in accordance with the PRISMA protocol. A literature search was performed from conception to September 2019 using PubMed, EMBASE and Web of Science. The results of eligible studies were appraised. A risk of bias analysis was carried out using Cochrane’s RoB 2.0 tool.

RESULTS

Fourteen studies were included in this review. A total of 279 subjects, including both human and animal were treated with UCMSCs. Four studies obtained UCMSCs from a third-party source and the remainder were harvested by the investigators. Out of the 14 studies, thirteen conducted xenogenic transplantation into nerve injury models. All studies reported significant improvement in nerve regeneration in the UCMSC treated groups compared with the various different controls and untreated groups.

CONCLUSION

The evidence summarised in this PRISMA systematic review of in vivo studies supports the notion that human UCMSC transplantation is an effective treatment option for peripheral nerve injury.